Generally, various substrate treatments using a substrate processing apparatus have been performed to clean or etch a substrate, such as a semiconductor wafer or a liquid crystal substrate, for manufacturing a semiconductor component or a flat display respectively.
A substrate processing apparatus includes a plurality of substrate processing units that process substrates using processing liquid, and a processing liquid supply part, which supplies processing liquid to the substrate processing units. The processing liquid supply part produces the processing liquid that has been diluted in a predetermined concentration, and stores the diluted processing liquid. The processing liquid supply part supplies the processing liquid, previously diluted to the predetermined concentration, to the substrate processing units simultaneously, while processing the substrate. For example, see Japanese Laid-Open Patent Publication No. 2007-123393.
In the substrate processing apparatus, if the flow rate of the processing liquid in a substrate processing unit is low, the processing liquid supply part cannot control the flow rate of the processing liquid, thereby failing to supply the predetermined flow of the processing liquid with high accuracy.
In addition, if the substrate processing apparatus produces the processing liquid that has been diluted in a certain concentration, and supplies the diluted processing liquid to the substrate processing unit after the production, the flow rate of the diluted liquid may be extremely low. In such a case the processing liquid supply part would be unable to control the concentration, thereby failing to supply the predetermined concentration of the processing liquid with high accuracy.
If the processing liquid having the flow rate that is used by all substrate processing units is supplied at all the times, the excess processing liquid that is unused by substrate processing units can be wasted. Thus, the usage efficiency of the processing liquid can be deteriorated.